The present embodiments relate to adaptive motion imaging. In medical diagnostic ultrasound imaging, motion imaging provides visualization of velocity, energy, variance or other motion characteristic of a fluid or tissue.
Medical diagnostic ultrasound imaging systems perform autocorrelation or Doppler processing between sets of received data to determine an average phase shift for fluid or tissue motion imaging. In Doppler processing, the phase shift represents the velocity of tissue or fluid. The energy of the phase shift and/or variance associated with the phase shift may also be used for imaging.
Acoustic energy is transmitted along a scan line, and echoes along the scan line are received. Multiple such transmit and receive events along each scan line are used to determine the phase shift. This phase shift represents the velocity towards or away from the transducer, a one-dimensional velocity. In vessels or other organs, the flow may be in a different direction than the scan line, resulting in inaccurate flow parameter estimation. To counteract this inaccuracy, the user may select settings for the steering angle.
The user sets a region of interest for motion imaging. For example, the region of interest is over a portion or cross section of a vessel. As the steering angle is adjusted, some of the region of interest may be shifted, resulting in the loss of motion imaging for a desired location.
The received signals are filtered prior to estimation of the motion parameters. A wall or clutter filter removes information from slowly moving objects, such as tissue, or removes information from rapidly moving objects, such as blood. A lack of sensitivity to slow or rapid movement due to the filtering may result in desired information being lost. Depending on the type, magnitude or other velocity characteristic, the user may have to reset wall or clutter filter controls for the desired sensitivity.
After estimation, thresholds may be applied, such as velocity and/or energy thresholds. If the velocity or energy for a given spatial location are below the respective thresholds, the velocity is set to a zero or other value. Similarly, spatial filtering may be applied. To avoid flash artifact, different amounts of spatial filtering may be applied depending on a temporal relationship of data. However, the spatial filtering or thresholding may not be optimal for a given situation.
User setting takes time and may be inconvenient. Different preset values for settings may not provide the optimum imaging. This poor plunkability results in longer scan times or sub-optimal imaging quality.